This is a proposal to collect longitudinal follow-up (second panel) data on a sub-sample of families with same-sex siblings (719 original families, 450 follow-up families) studied during 1988-1990. The original families consisted of six groups, (1) MZ twins, (2) DZ twins, (3) Step families with full siblings, (4) Step families with half siblings, (5) Step families with genetically unrelated children, (6) Non-divorced families with full siblings. A major goal of the initial project was to estimate shared environment influences and additive and non-additive genetic influences on environmental measures. The particular configuration of families was chosen to maximize the conceptual power of the design rather than precisely estimated the magnitude of effects on a representative sample of the U.S. The sample, however, is a very broad one relative to those used in other developmental studies. In the follow-up study the investigator plan to assess 7 domains of the environment, Parent-child interactions (7 measures, including a videotaped segment), sibling interaction, (5 measures, including a videotapes segment), relationships with non-residential parent(1 instrument), peer relationships (1 instrument), peer relationships (1 instrument), other (Life Event checklist, Social support). Also included are three domains of outcome measures; Mental health/Illness indicators (5 measures, 1 videotaped segment), Personality Developmental strengths (7 measures, 1 videotaped), and Child pubertal status (1 measure). A number of characteristics of the family that may moderate non-shared environmental effects are also assessed; General stressors (1 measure) and Martial conflict (4 measures, 1 videotaped segment). In addition, standard social and demographic information is gathered. The data will be collected by interviewers hired and trained by the National Opinion Research Center (NORC) on two occasion one week apart. The purpose of a longitudinal component is to allow the investigators to address a series of complex questions regarding the dynamics of change on the wide variety of measures proposed(e.g., does the relative influence of heredity and environment on change over time?)